Today | Weather | Friday, September 18, 2026

Weather in Redwood City, California

07:56 PM
Now
Cloudy Night
68° F
Feels Like 66°
Precipitation 0 %
Wind 8 mph
Humidity 69 %
Today
Cloudy Night
Day 81°
Night 57°
Precipitation 0 %
Wind 6 mph

Redwood City Weather Forecast Updated

27 minutes ago
Last updated on
Weather Forecast History
Last Year's Weather on This Day (September 18, 2025)
Rainy Weather

Day

77°

Night

63°

Wind

6 mph

Precipitation

96 %

Air Quality in Redwood City

NOW
41 AQI
Good air quality Dominant pollutant: O3

Pollutant Concentrations:

PM2.5 5.95 µg/m³
PM10 18.12 µg/m³
O3 0.044 ppm
NO2 0.3 ppb
SO2 0.3 ppb
CO 0.13 ppm
NH3 0 µg/m³
NO 0 µg/m³
PM2.5 – Fine particles <2.5μm
PM10 – Inhalable particles <10μm
O3 – Ozone
NO2 – Nitrogen dioxide
SO2 – Sulfur dioxide
CO – Carbon monoxide
NH3 – Ammonia
NO – Nitric oxide

Health Recommendations:

Air quality is considered satisfactory, and air pollution poses little or no risk.

Show raw pollutant concentrations (µg/m³)
PM2.55.95 µg/m³
PM1018.12 µg/m³
O387.08 µg/m³
NO20.62 µg/m³
SO20.74 µg/m³
CO147.86 µg/m³
NH30 µg/m³
NO0 µg/m³